typo partial index doc

Author: SachinBhandari

source/core/index-partial.txt

@@ -67,7 +67,7 @@ For example, given the following index:
 
 The following query can use the index since the query predicate
 includes the condition ``rating: { $gte: 8 }`` that matches a subset of
-documents matched by the index filter expression ``ratings: { $gt: 5
+documents matched by the index filter expression ``rating: { $gt: 5
 }``:
 
 .. code-block:: javascript